Review: Zone3 Bouyancy Shorts : ROKA Sim Pro : Bluesevently Core Short go Head-to-head

IMG_3756What are buoyancy/core shorts?

Essentially they are a cut-down wetsuit to ‘shorts/jammers’ size.

Why core shorts?

They replace the pull buoy – swim training without the drag, inconvenience and kick restriction of the pull buoy.


Improved body position and all that comes with that.


They are effective at what they do but that effectiveness encourages over-use and over-reliance; leading ultimately to poor kick.

Test Methdology

My unscientific methodology was to use the Zone3 for an extended, pre-spring, training period in the pool. Then switch to two other competitor products to feel the differences (if any).

The test is a little unfair on the Zone3 as I used their shorts to the point where the structure of the shorts started to degrade. On the other hand, the advantage of this is that it highlights areas to watch out for in the competitor products but there simply is not the extended period of MANY months to get 3 or more pairs of these shorts to the point of breaking. So the others may or may not last as long as the Zone3.

The main advantage is that an extended period of use leads to detailed familiarisation and any variations supplied by the others are more readily noted.

So please bear this in mind as you read on.


The Zone3 is the ‘shorter’ of the shorts (jammers). In theory there is less material and hence less buoyancy. The Blueseventy has a larger piece of thinner side material. All three effectively use the same neoprene.

However, there is no material difference in their buoyancy.


The Zone3’s design has been around for a few years. I’m not sure about the other two. The other two both look more modern and win on the aesthetics. Personally I prefer the ROKA. You may prefer the looks of either of the other two.



The fit IS different on each model.

Here are the sizing charts to start off:

Source: Blueseventy

Source: ROKA
Source: ROKA
Source: Zone3
Source: Zone3

My suggestion would be to get the smallest that seems to fit from the sizing chart. So if you are a 32 I would go for the SMALL in Zone3, if you are a 31 I would go for the small in the Blueseventy and for the ROKA they are less ambiguous in the sizing chart.

They need to be tight – you won’t get much more than speedos on underneath them. But also over time the draw strings come harder to tighten the material. You are then left with a flap at the rear acting as a mini parachute to slow you down.

This parachute effect is particularly bad with the Zone3. I don’t think the same will happen with the other two as the ‘cut’ is NOTICEABLY lower to the rear. The material is not there for the parachute to exist to the same degree.

Pretty Similar Materials

I have relatively chunky ‘bike thighs’ but that was fine.

The differently constructed side panels of the Blueseventy and of the ROKA meant that the could be put on much more easily and fitted more comfortably, in my opinion.

The Fit of the ROKA was the best for me but of course you are a different size to me.

Motion/Movement Restriction

I don’t think the design of the panels and the different thicknesses made any difference to the physical act of swimming between the three shorts. They all performed identically in that respect.

Racing & Usage

And this is how fast you might go. I just liked the image. Other than the presence of neoprene, a person and water it’s not really relevant.

You can use them wherever you want. In pool-based races they are illegal. I would imagine that in ‘WETSUIT MANDATORY’ races you would be unable to use them but you would be able to use them in WETSUIT OPTIONAL RACES.

You might want to try cycling and running in them…I wouldn’t. Even for an aquathlon; I wouldn’t fancy running 5k in a pair.

Pool training usage is recommended in lieu of a pull buoy. Many people use them 100% of the time. I have heard from others that this then weakens their kick effectiveness noticeably. It could be argued that you don’t kick much in triathlon but I am not sure I buy into that argument. Still; it’s worth bearing in mind.

Who uses them

There’s normally a couple of people (male triathletes) wearing these when I go training. Most people leave them on for the full session. For people doing 400m in 6 minutes or 400m in 9 minutes – there seems to be no particular pattern to those who wear them in the ‘normal’ ability range. I’ve never seen beginners use them and I’ve never seen the really good national AG level (champions) swimmers use them. Maybe they do…I don’t swim in that lane 🙂


As I alluded to earlier this is a little unfair on the Zone3 that I wore MUCH more. Each of the shorts should easily last a year of 2-3x a week usage as part of a main session. IE I am assuming that you do not use them exclusively for pool swimming like many people do. In which case they may JUST about last a year but probably not.

Here is a close-up of the Zone3 (below). As the waist gets looser over time you have to tighten the cord more. As you tighten it more then material starts to more quickly deteriorate. Ideally they should have an elasticated waist. This will most likely happen equally to all brands.

I once tried a plastic draw-string device but that was unable to hold the cord tight enough for me to then tie a knot/bow over it. However I have heard of others who have had success with that approach.


You can also just see at the top of the photo that the Zone3 seams are starting to separate. This is happening to other seams as well. Black Witch paste will fix that, as it would a wetsuit, but I would rather buy a new pair myself. Some of the aspects of the Blueseventy and ROKA construction (eg thicker bonding to the sides) suggest that this would not happen quite so easily to them – especially to the ROKA.

So again ROKA would just edge it here over the Blueseventy and Zone3.


Ahem. It’s easier to ‘wee’ with the ROKA and Blueseventy. Say no more; it’s still quite possible with the Zone3.

Women: I imagine there is no reason why women could not wear them and get the same benefits. Sizing may be different.


At upwards of £45 these are not cheap. I could only find the ROKA on Wiggle and I don’t get a penny if you buy them there.

June 2015Amazon Price
Zone3 Bouyancy Shorts£48.00Link
ROKA Sim Pro£99.00Link
Blueseventy Core Short£65.00Link


For personal fit, aesthetics and supposed longevity of design, the ROKA SIM PRO easily wins for me. A bit tight; but they will ‘give’ over time. A bit low at the front; but I’ll be careful ALL the time 🙂

My worry about the Zone3 and Blueseventy is the lack of a low cut to the rear and the deterioration of the seams.

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1 thought on “Review: Zone3 Bouyancy Shorts : ROKA Sim Pro : Bluesevently Core Short go Head-to-head

  1. good reviews zone3 bouyance shorts my waist is 38 inches would you recommend size Lge or XL
    Regards, steve

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